Device to device communication with cluster coordinating

ABSTRACT

Technology for a user equipment (UE) to communicate in a device to device (D2D) network. A D2D discovery beacon can be listened for at the UE for a predetermined period of time. The UE can be self-assigned as a D2D cluster coordinator when the D2D discovery beacon has not been received by the UE for the predetermined period of time. A D2D cluster can be formed to enable D2D communication between D2D UEs in the D2D cluster. A D2D discovery beacon can be transmitted from the D2D cluster coordinator to the D2D UEs within the D2D cluster.

RELATED APPLICATIONS

This application claims the benefit of and hereby incorporates by reference U.S. Provisional Patent Application Ser. No. 61/768,330, filed Feb. 22, 2013, with an attorney docket number P54652Z.

BACKGROUND

Users of wireless and mobile networking technologies are increasingly using their mobile devices to communicate as well as send and receive data. With increased data communications on wireless networks, the strain on the limited resources for telecommunications is also increasing.

To handle the increasing amount of wireless services for an increasing numbers of users, efficient use of the available radio network resources has become important. Device to Device (D2D) communications allows mobile users to directly communicate with each other with little or no burden on a wireless network. The D2D communication can occur when adjacently located devices are enabled to communicate with each other directly instead of using a conventional communications links such as a Wi-Fi or cellular communications system. D2D communications may occur within range of a cellular communications system, such as an enhanced node B (eNB). The cellular communication system can assist with the D2D communication.

D2D communications can also occur outside of the range of a cellular communications system or where a cellular communications system is unavailable, e.g. non-network assisted. In either case, network-assisted or non-network assisted D2D communications can be coordinated to achieve higher spatial reuse, manage interference, and limit control and feedback overhead.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosure; and, wherein:

FIG. 1 depicts a D2D communication centralized scheduling scheme in accordance with an example;

FIG. 2 shows a downlink radio frame structure in accordance with an example;

FIG. 3 depicts a network-assisted cluster based architecture in accordance with an example;

FIG. 4 illustrates a non-network assisted cluster based architecture in accordance with an example;

FIG. 5 illustrates a self-elected cluster coordinator discovering D2D devices in a D2D cluster in accordance with an example;

FIG. 6 shows a core network server or D2D server setting up a D2D radio bearer to pair D2D UEs together in accordance with an example;

FIG. 7 depicts a bandwidth allocation scheme for a network-assisted cluster based architecture in accordance with an example;

FIG. 8 depicts a bandwidth allocation scheme for a non-network assisted cluster based architecture in accordance with an example;

FIGS. 9 a and 9 b show examples of frame and symbol structures using a D2D subframe structure in accordance with an example;

FIG. 10 depicts the functionality of computer circuitry with a UE operable to communicate in a D2D network in accordance with an example;

FIG. 11 depicts the functionality of computer circuitry with a UE operable to communicate in a D2D network in accordance with an example;

FIG. 12 depicts the functionality of computer circuitry with an enhanced node B (eNB) operable to form a D2D communication cluster in accordance with an example;

FIG. 13 illustrates a method for forming a D2D communication cluster in accordance with an example;

FIG. 14 illustrates a diagram of a UE in accordance with an example.

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element. Numbers provided in flow charts and processes are provided for clarity in illustrating steps and operations and do not necessarily indicate a particular order or sequence.

Direct communication between mobile wireless devices that are located close to or adjacent each other can be advantageous to alleviate the signaling overhead and signal interference between devices and nodes in a cellular network. Device to device (D2D) or machine type communication refers to direct communication among devices or machines without routing the data through a communications network, such as a cellular network or a wireless fidelity (WiFi) network.

Clustering closely located D2D devices, such as user equipments (UEs) that are capable of D2D or local communication is a feasible and efficient way of increasing data demands on cellular networks while alleviating signaling overhead and managing interference. In D2D communication, devices can be grouped into clusters, where at least one device sends data to another device in a cluster. A cluster can comprise multiple D2D devices that are located nearby or adjacent each other. A cluster can also comprise multiple D2D devices that can locally communicate with other D2D devices directly. A cluster can also comprise grouping together D2D devices with mutual or similar properties or characteristics.

The D2D devices in a cluster can be grouped into clusters based on the relative location of a D2D UE to other D2D UEs or based on other criteria, such as similar data requirements. D2D devices in a cluster can directly share the resources with other D2D devices. In one embodiment, D2D devices in a cluster can share resources by competing for allocated resources. In another embodiment, D2D device in a cluster can directly share resources by having one of the D2D devices allocate the resources. In one embodiment the resources may be allocated between cluster members based on a resource allocation grant by the cellular network. In one embodiment, the resources may also be allocated independent of a cellular network and be allocated using a D2D cluster coordinator.

In a D2D communications system there are several D2D communication system schemes where multiple mobile equipment devices, such as UE, can directly communicate with each other and/or communicate with a cellular communications system, such as an enhanced node B (eNB) or base station.

One D2D communication system scheme is an in-network or network assisted scheme that has a central controller, such as an eNB or a base station, receiving transmission requests from all the UEs in the D2D communications system. In another embodiment, a D2D communications system can be integrated into a cellular network, where an eNB can allocate resources for the cluster and a D2D coordinator then allocates the resources to each cluster member, such as each D2D device. In another embodiment, the D2D coordinator can assign subsets of resources to nearby devices in a cluster.

The cellular communications system can comprise one or more cellular network nodes and one or more Institute of Electrical and Electronics Engineers (IEEE) 802.11-2012 configured access points. In one embodiment, the one or more cellular networks may be 3rd generation partnership project (3GPP) long term evolution (LTE) Rel. 8, 9, 10, or 11 networks and/or IEEE 802.16p, 802.16n, 802.16m-2011, 802.16h-2010, 802.16j-2009, 802.16-2009 networks.

The D2D coordinator collects all the D2D communication requests within the cluster. The cellular network node can take all the requests from UE coordinators within the cell. The cellular network node can semi-statically allocate a large amount of resources per cluster. The cluster coordinator can be responsible for resource allocation of each D2D pair within the cluster. One advantage of a two tier resource allocation, where the D2D coordinator and the cellular network node allocate resources, is that the two tier resource allocation can dramatically reduced the signaling overhead from the cellular network node and reduce the feedback overhead from UE to cellular network node.

When D2D communication takes place within a cellular network, the cluster can operate on uplink (UL) or downlink (DL) resources. For UL resources, an UL resource allocation grant can be reused for network controlled cluster operation. The network-assisted cluster scheduling operation can lower the threshold for adapting user cooperation schemes between D2D capable UEs or other types of mobile users and can help to permit efficient data transfer between cluster members.

FIG. 1 illustrates one embodiment of a D2D communication centralized scheduling scheme that has a central controller, such as eNB or a base station. The centralized controller 110 in the centralized scheduling scheme can comprise a transceiver 120 and a computer processor 130. FIG. 1 also illustrates that the UE 140 can comprise a transceiver 150 and a computer processor 160.

D2D communication systems may provide mobile device users with better quality of service (QoS), new applications, and increased mobility support. To increase efficiency and reduce interference, UEs in a D2D system can synchronize their D2D communications. In one example, the UEs synchronize within the D2D network using a radio frame structure, transmitted on a physical (PHY) layer in a DL or UL transmission between an eNB and a D2D UE. In one embodiment, the D2D communications may occur on a licensed band for communications. In one embodiment a 3GPP LTE frame structure is used for the synchronization. In one embodiment, the one or more cellular networks may a 3GPP LTE Rel. 8, 9, 10, 11, or 12 network and/or a IEEE 802.16p, 802.16n, 802.16m-2011, 802.16h-2010, 802.16j-2009, 802.16-2009.

FIG. 2 illustrates a downlink radio frame structure. In another embodiment, an uplink radio frame structure could similarly be used. In the example of the downlink radio frame structure, a radio frame 200 of a signal used to transmit the data can be configured to have a duration, Tf, of 10 milliseconds (ms). Each radio frame can be segmented or divided into ten subframes 210 i that are each 1 ms long. Each subframe can be further subdivided into two slots 220 a and 220 b, each with a duration, Tslot, of 0.5 ms. The first slot (#0) 220 a can include a legacy physical downlink control channel (PDCCH) 260 and/or a PDSCH 266, and the second slot (#1) 220 b can include data transmitted using the PDSCH. Additional structures may also be used, such as enhanced structures for enhanced PDCCH (ePDCCH) or other types of enhanced channels.

Each slot for a component carrier (CC) used by the node and the wireless device can include multiple RBs 230 a, 230 b, 230 i, 230 m, and 230 n based on the CC frequency bandwidth. Each RB (physical RB or PRB) 230 i can include 12-15kHz subcarriers 236 (on the frequency axis) and 6 or 7 orthogonal frequency-division multiplexing (OFDM) symbols 232 (on the time axis) per slot. The RB can use seven OFDM symbols if a short or normal cyclic prefix is employed. The RB can use six OFDM symbols if an extended cyclic prefix is used. The RB can be mapped to 84 resource elements (REs) 240 i using short or normal cyclic prefixing, or the RB can be mapped to 72 REs (not shown) using extended cyclic prefixing. The RE can be a unit of one OFDM symbol 242 by one subcarrier (i.e., 15 kHz) 246.

When communicating with each other, each D2D UE may need to switch between transmission and reception modes for sending and receiving messages, respectively. In one embodiment, D2D communications can be performed during the UL band communications period of a cellular network. In this embodiment, the sequential switching between the transmission and reception modes may enable UEs to perform D2D communications during the UL band communications period of a cellular network. In another embodiment, D2D communications may be performed during the DL band communications period of a cellular network. In this embodiment, the sequential switching between the transmission and reception modes may enable UEs to perform D2D communications during a DL band communications period of a cellular network.

FIG. 3 shows multiple mobile devices or UEs 340, 350, and 360 located nearby or adjacent each other which can be assigned or formed into D2D clusters. In one embodiment, if a D2D UE wants to start the D2D communication, after the D2D discovery process, the D2D UE will scan for a D2D cluster discovery beacon to determine whether there is an existing D2D cluster within range of the D2D UE. If the D2D UE cannot find an existing cluster, the D2D UE wants to start a D2D cluster and the D2D UE can send a forming cluster request message to the eNB 330. When the D2D UE receives a grant from the eNB 330, the D2D UE can start a D2D cluster discovery beacon. Nearby D2D pairs that detect the cluster beacon can join the cluster. This may be desirable in a case of a D2D cluster operation in which the cluster comprises more than two locally communicating devices or UEs.

FIG. 3 also illustrates one embodiment of a network-assisted cluster based architecture with a UE coordinator. In a network-assisted cluster based architecture, multiple D2D UEs 340, 350, and 360 can be assigned or formed into D2D clusters. One of the D2D UEs may serve as a cluster coordinator 360, coordinating the channel accesses of the D2D UEs 340, 350, and 360. In one embodiment, the D2D UEs can be assigned as pairs for D2D communication, such as a transmitter D2D UE 340 and receiver D2D UE 350. In one embodiment, D2D UEs 340, 350, 360, and/or 390 and eNB 330 can work together to determine if the cluster should be formed and which UE is the cluster coordinator 360. In one embodiment, the eNB 330 can form the clusters 310, 320, 370, and 380 based on the approximate location of each UE in the network. In one embodiment, if D2D UEs 390 are not located within a defined distance or signal strength of each other, a cluster may not be formed and the UEs 390 can communicate with other UEs via the eNB 330.

In one embodiment where clusters 370 and 380 overlap, the eNB can assign different resource blocks to each of the overlapping clusters. For example if cluster 1 (370) and cluster 2 (380) overlap, the eNB can assign RBs 1 through 10 to overlapping cluster 1 (370) and RBs 11 through 20 to overlapping cluster 2 (380). In another embodiment where clusters 310 and 320 do not overlap, the eNB can reuse the same RBs and assign RBs 1 through 20 to each of the non-overlapping clusters.

In one embodiment, selected UEs can be assigned as high category UEs. High category UEs are UEs that have some increased or additional functionality beyond the normal functionality of a UE in order to be a cluster coordinator. In one embodiment, only high category UEs may be assigned as a cluster coordinator 360. For example, a D2D UE with a battery level capacity that exceeds a selected threshold may be assigned as a high category UE. In one embodiment, the high category UEs can self-elect to be a cluster coordinator. In one embodiment, the eNB can ratify the first D2D UE that volunteers to be the cluster coordinator with a battery level capacity that exceeds a selected threshold for a cluster coordinator. In one embodiment, the cluster coordinator may not be involved in any D2D communication and may only be facilitator.

FIG. 4 illustrates a non-network assisted cluster based architecture 400 with a cluster coordinator 460. In a non-network assisted cluster based architecture, multiple D2D UEs 440, 450, and 460 can be assigned or formed into D2D clusters. One of the D2D UEs may serve as a cluster coordinator 460, coordinating the channel accesses of the D2D UEs 440, 450, and 460. In one embodiment, the D2D UEs can be assigned as pairs for D2D communication, such as a transmitter (Tx) D2D UE 440 and receiver (Rx) D2D UE 450. In one embodiment, D2D UEs 440, 450, 460, and/or 430 can work together to decide if a cluster should be formed and which D2D UE is assigned or selected as the cluster coordinator 460. In one embodiment, each cluster coordinator can form a cluster, such as clusters 410, 420, 470, and 480 respectively based on the approximate location of each D2D UE in the network. In one embodiment, if D2D UEs 490 are not located within a defined distance or signal strength of other D2D UEs, a cluster may not be formed and the D2D UEs 430 can communicate directly or indirectly with one or more clusters 410, 420, 470, and/or 480. In one embodiment, a D2D pair 440 and 450 can belong to multiple clusters, such as overlapping cluster 1 (470) and overlapping cluster 2 (480). In another embodiment, a D2D pair 440 and 450 can belong to choose one cluster to join from a plurality of clusters such as overlapping cluster 1 (470) and overlapping cluster 2 (480).

In one embodiment, a UE can self-elect as a coordinator, such as a D2D coordinator, cluster coordinator, or UE coordinator. To determine if a cluster coordinator is needed, the UE may listen for a selected period of time for a discovery beacon from another D2D UE. When the

UE does not hear or receive a discover beacon within the selected period of time, the UE can elect itself as the cluster coordinator.

In one embodiment, the UE can assess if the UE meets the cluster coordinator requirements before electing itself as cluster coordinator. In one embodiment, the cluster coordinator requirements may include a battery capacity level threshold or a transmit power threshold. In another embodiment, if the UE meets the cluster coordinator requirements then the UE can elect itself as the cluster coordinator. In one embodiment, the cluster coordinator can determine the size of the cluster. The size of the cluster may be determined based on a coverage range of the cluster coordinator. In one embodiment the coverage range can be based on the power level of the cluster coordinator.

FIG. 5 illustrates that when a cluster coordinator 560 has been selected or self-elected, the cluster coordinator 560 can broadcast a discovery beacon 570 to be received by adjacent D2D UEs, such as D2D UEs 510-550, to discover the D2D devices in a D2D cluster. In one embodiment, the cluster coordinator 560 can receive requests to join the D2D cluster from UEs outside of the D2D cluster. In one embodiment, the discovery beacon sent by the cluster coordinator 560 can be a reserved set of sequences out of the total set of discovery sequences. In another embodiment, the discovery beacon can also be a short data packet. The short data packet can include the cluster coordinator's identification (ID) and information related to forming a cluster. In one embodiment, the cluster discovery beacon may be sent at selected time periods or at regular intervals. In one embodiment, a D2D UE such as D2D UEs 510-550 can use the receive power of the discovery beacon as a reference to determine D2D UE cluster association, cluster dissociation, and cluster handover decisions. In one embodiment, the cluster coordinator can assign RBs to the cluster to reduce or eliminate interference between UEs in the cluster and with UEs in adjacent clusters.

In one embodiment, when a D2D UE moves out of the range of the cluster coordinator 560, dissociation can occur. For example, a D2D UE associated with a cluster may monitor the received discovery beacon power. If the received beacon power drops below a selected level or threshold, the D2D UE may dissociate with the cluster. In another embodiment, a cluster handover, such as a handover of a D2D communication back to an uplink transmission, is performed by a core network or eNB. In one embodiment, a core network server or D2D server can control the handover between D2D transmission and normal UL transmission. For a non-network assisted cluster based architecture, a core network server or D2D server may not be used because all safety related information is broadcasted and each D2D UE has the same QoS.

In one embodiment, the association of a D2D UE with a cluster coordinator may be assisted by an eNB. For example, a D2D UE who can receive the discovery beacon and is not a member of the cluster may send an acknowledgment message to an eNB and the eNB will relay the acknowledgment message to the cluster coordinator. In another embodiment, the association of a D2D UE with a cluster coordinator 560 may be non-network assisted. For example, a D2D UE that is not a member of the cluster can receive the discovery beacon and directly send an acknowledgment message to the cluster coordinator.

An acknowledgement message may have several different formats. In one embodiment, the acknowledgement message is a physical layer acknowledgement (PHY ACK). For a PHY ACK, a D2D UE can simply reply back with a beacon at certain time/frequency slots. In another embodiment, the acknowledgement message is a medium access control (MAC) packet. For a MAC packet, the D2D UE will send the acknowledgement message as a payload and transmit the acknowledgement message through a random access channel. In one example, a D2D UE that desires to join a cluster may not send an ACK to the cluster coordinator directly. Instead, the UE can send a request to the eNB for criteria matching. If the selected criteria are matched, the eNB may let the cluster coordinator and the D2D UE know that the D2D UE desires to join the cluster, at which point further association steps can be performed.

FIG. 5 further illustrates that a D2D UE may listen for and/or receive multiple discovery beacons and may identify multiple nearby or adjacent clusters. The D2D UE can select one or more clusters to associate with. When a D2D UE, such as Tx D2D UEs and Rx D2D UEs 510-550, select a cluster to associate with, each D2D UE can send a join request 580 to the cluster coordinator 560 requesting to join the cluster.

In one embodiment, each cluster has one cluster coordinator 560. In another embodiment, the cluster coordinator assignment or role may alternate between multiple UEs over a period of time. One advantage to alternating which UE is the cluster coordinator 560 is that the UEs that are cluster coordinators 560 for a period of time can save power during the period that the UE is not the cluster coordinator 560. In another embodiment, the cluster coordinator 560 may alternate to another UE when the current cluster coordinator's battery level falls below a selected threshold. In one embodiment, to alternate the cluster coordinator assignment, the current cluster coordinator and the UE that want to be the next cluster coordinator, e.g. the future cluster coordinator, can alternate or switch the cluster coordinator role using D2D broadcast communication.

A non-network assisted D2D communications system can be advantageous for a public safety usage situation. In one embodiment, a cluster coordinator can serve as a mobile Pico node. In one embodiment, the location and coverage of the mobile Pico node is dynamically optimized based on D2D traffic. In another embodiment, the cluster coordinator can be a D2D UE with a battery capacity level that is higher than a selected threshold.

In a network-assisted environment, the cluster coordinator can communicate with eNB to: request or release D2D bandwidth for the whole cluster; report interference among clusters for combing or splitting the cluster; request to change the transmit power; request to move to a different frequency band; or request to add or remove a D2D UE to or from the cluster. In a non-network assisted environment, the cluster coordinators between different clusters can directly: request or release D2D bandwidth for the whole cluster; report interference among clusters for combing or splitting the cluster; request to change the transmit power; request to move to a different frequency band; or request to add or remove a D2D UE to or from the cluster. For overlapping clusters a D2D UE can determine which cluster is best or join multiple clusters.

FIG. 6 illustrates that for a network-assisted cluster based architecture 600, a core network server or D2D server can set up a D2D radio bearer to pair D2D UEs and to ensure quality of service (QoS) control. The eNB and/or the core network can set up the D2D UE data communication radio bearer. In one embodiment, a radio bearer is a link between two points that meet a defined or selected characteristic. In one embodiment, a selected characteristic is the proximity of D2D UEs, such as D2D UE pairs 610 and 620, 630 and 640, or 650 and 660. In one embodiment, for a UE associated with a radio bearer, the radio bearer can specify a configuration for layer 2 and physical layer communication in order to have its QoS clearly defined. In another embodiment, radio bearers are layer 2 or higher for the transfer of either the UE data or control data.

In one embodiment, if a cluster coordinator discovers that a D2D UE pair is within direct communication range, then the cluster coordinator can send a request to the eNB and core network to request the setup of a radio bearer and corresponding QoS. In another embodiment, a corresponding D2D radio network temporary identifier (RNTI) can also be granted for D2D communication. In one embodiment, the D2D RNTI is sent to both the transmitter D2D UE and the receiver D2D UEs such that the Rx D2D UE knows it is the addressed or receiving D2D UE for D2D communication.

FIG. 7 illustrates a network-assisted cluster based architecture where a Tx D2D UE, such as Tx D2D UEs 720, 730, and 760, has data to communicate to an Rx D2D UE, such as Rx D2D UEs 740, 750 or 710. When the Tx D2D UE has data to communicate, the Tx D2D UE will send a bandwidth request 770 to the eNB 700 and the UE coordinator 710. The bandwidth request 770 can be a contention based transmission in the bandwidth request zone. Bandwidth request 770 may consist of two portions, a contention code or preamble and a request message payload. The contention code can be used as a channel training signal for detecting a request message. When a collision occurs, the coordinator may still be able to detect multiple collided contention codes though the collided request messages may be lost. If the request message is successfully decoded, the coordinator may grant the resource. If the request message is lost but the code is detected, the coordinator may ask the transmitter which sent the code to submit the request message in an allocated resource.

If bandwidth is allocated by the UE coordinator 710 for multiple transmissions by a Tx D2D UE 720, 730, or 760 to Rx D2D UEs 710, 740, or 750, the D2D UE receivers may receive a bandwidth allocation grant 780 from the eNB 700 and/or the UE coordinator 710 that includes a notification of the multiple transmissions bandwidth allocation grant.

FIG. 8 illustrates a non-network assisted cluster based D2D communications architecture. In the non-network assisted cluster based D2D communications architecture the UE coordinator 810 coordinates communications between D2D UEs 810-860 within the cluster. To coordinate D2D communications between D2D UEs 810-860, the UE coordinator 810 can receive bandwidth requests 870 from Tx D2D UEs 810, 830, and 860 within the cluster and broadcast resource allocations 880 to D2D UEs in the cluster. In one embodiment, Tx D2D UEs 810, 830, and/or 860 send a bandwidth request 870 to the UE coordinator 810. The UE coordinator 810 can receive the bandwidth request from the D2D transmitter 810, 830, and/or 860 and can allocate bandwidth for the D2D transmission. The UE coordinator 810 can communicate a bandwidth allocation grant 880 to D2D UEs 820-860 in the cluster. In one embodiment, the bandwidth allocation grant may be unicast to a Tx D2D UE and a RX D2D UE pair. In one embodiment, only the Tx D2D UE and the Rx D2D UE pair, such as pairs 810 and 820, 830 and 840, or 850 and 860, can decode the bandwidth allocation grant. In another embodiment, the UE coordinator 810 may broadcast the allocation grants to the D2D UEs within the cluster. In one embodiment, a Tx D2D UE may request resources or bandwidth for multicast transmissions.

In one embodiment, the bandwidth allocation grant 880 can include D2D communication scheduling information, including: when a D2D UE pair can communicate data, the period of time the D2D UE pair can communicate for, and/or the amount of bandwidth allocated for the D2D communication. The scheduling information can be applied in a future subframe, e.g. the next subframe, of the bandwidth allocation grant. In one embodiment, a D2D data communication uses an UL carrier or UL subframes in a time division duplex (TDD) system. In another embodiment, a transmitted waveform can follow either a DL frequency division multiple access (OFDMA) waveform or UL single carrier frequency division multiple access (SCFDMA) waveform. One advantage of using a DL OFDMA waveform is a reduction in UE implementation complexity because the D2D reception can share the hardware of the normal downlink.

FIGS. 9 a and 9 b show examples of frame structures and symbol structures using a D2D subframe structure. The scheduling information 950 is a communications schedule for D2D communications. In one embodiment, a D2D subframe 3 is where data transmission 960 occurs. In another embodiment, the RS can reuse DL cell-specific reference signal (CRS) port 0 and port 1 for one or two stream transmissions. In another embodiment, the CRS will also be used for other measurements, such as D2D transmission power control and adaptive coding and modulation. In one embodiment, the contents in the scheduling information 950 can follow a current downlink control information (DCI) or a simplified DCI for D2D transmission. In one embodiment, the D2D subframe structure is a UL subframe structure. In another embodiment, the D2D subframe structure is a DL subframe structure. In one embodiment, the random access zone 940 is a bandwidth request zone or a contentions zone to request bandwidth from the cluster coordinator.

In one embodiment, the reference signal structure may be different from the CRS since there is no periodic reference signal sent on the link. In another embodiment, a reference symbol may be used for OFDMA modulation. The reference symbol enables automatic gain control (AGC) setting and channel estimation at the receiver for burst traffic.

FIG. 10 provides a flow chart 1000 to illustrate the functionality of one embodiment of the computer circuitry with a UE operable to communicate in a D2D network. The functionality can be implemented as a method or the functionality can be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The computer circuitry can be configured to listen for a D2D discovery beacon at the UE for a predetermined period of time, as in block 1010. The computer circuitry can be further configured to self-assign the UE as a D2D cluster coordinator when the D2D discovery beacon has not been received by the UE for the predetermined period of time, as in block 1020. The computer circuitry can also be configured to form a D2D cluster to enable D2D communication between D2D UEs in the D2D cluster, as in block 1030. The computer circuitry can also be configured to transmit a D2D discovery beacon from the D2D cluster coordinator to the D2D UEs within the D2D cluster, as in block 1040.

In one embodiment, the computer circuitry is further configured to receive a join request at the D2D cluster coordinator from a D2D UE in the D2D cluster to join the D2D cluster and communicate a join request approval to the D2D UE. In another embodiment, the computer circuitry is further configured to receive a D2D bandwidth allocation request for bandwidth from at least one D2D UE in the D2D cluster, schedule a communication period for the at least one D2D UE in the D2D cluster, and transmit scheduling information for the communication period to the at least one D2D UE in the D2D cluster to enable the at least one D2D UE to determine when the bandwidth is allocated for the at least one D2D UE to communicate with another D2D UE in the D2D cluster. In another embodiment, the computer circuitry is further configured to coordinate scheduling information of each of the D2D UEs in the D2D cluster to reduce interference between the D2D UEs.

FIG. 11 provides a flow chart 1100 to illustrate the functionality of one embodiment of the computer circuitry with a UE operable to communicate in a D2D network. The functionality can be implemented as a method or the functionality can be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The computer circuitry can be configured to receive, at the UE, a D2D discovery beacon from a D2D UE coordinator in a D2D communication cluster, as in block 1110. The computer circuitry can be further configured to transmit a join request to the D2D UE coordinator, to join the D2D communication cluster, as in block 1120. The computer circuitry can also be configured to receive a join request approval message to join the D2D communication cluster, as in block 1130.

In one embodiment, the computer circuitry is further configured to transmit a D2D bandwidth allocation request to the D2D UE coordinator in the D2D communication cluster, receive a scheduling information from the D2D UE coordinator for communicating with a D2D UE in the D2D communication cluster, and transmit data from the UE to the D2D UE in the D2D communication cluster at a selected time based on the received scheduling information. In another embodiment, the computer circuitry is further configured to transmit a join request to an adjacent D2D UE coordinator that is located in an adjacent D2D communication cluster to the D2D communication cluster. In another embodiment, the computer circuitry is further configured to send a multicast transmission request to the D2D UE coordinator to schedule a multicast by the UE to other UEs in the D2D communication cluster. In another embodiment, the computer circuitry is further configured to request to associate or request to dissociate with the D2D UE coordinator based on a receiving power of the D2D discovery beacon at the UE. In one embodiment, the computer circuitry is further configured to request a handover from the D2D UE coordinator to another D2D UE coordinator based on a receiving power of the D2D discovery beacon at the UE. In another embodiment, the computer circuitry is further configured to receive D2D discovery beacons at the UE from a plurality of D2D UE coordinators, wherein each D2D UE coordinator is located in a separate D2D communication cluster.

FIG. 12 provides a flow chart 1200 to illustrate the functionality of one embodiment of the computer circuitry with an eNB operable to form a D2D communication cluster. The functionality can be implemented as a method or the functionality can be executed as instructions on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The computer circuitry can be configured to receive a D2D cluster coordinator self-assignment request from a UE at an eNB, as in block 1210. The computer circuitry can be further configured to transmit a D2D cluster coordinator assignment acceptance from the eNB to the UE to form a D2D cluster coordinator UE, as in block 1220. The computer circuitry can also be configured to form a D2D cluster by the eNB to enable D2D communication between D2D UEs, as in block 1230. In one embodiment, the D2D cluster coordinator UE coordinates the D2D communication between the D2D UEs in the D2D cluster.

In one embodiment, the computer circuitry is further configured to receive a D2D radio bearer setup request from another UE in the D2D cluster at the eNB and establishing a D2D radio bearer for a D2D pair that includes the other UE. In another embodiment, the computer circuitry is further configured to establish the D2D radio bearer to provide a desired quality of service (QoS). In another embodiment, the computer circuitry is further configured to determine a D2D cluster coordinator UE in the D2D cluster to receive the D2D cluster coordinator assignment based on a power capacity level or a battery capacity level threshold of the UE in the D2D cluster. In another embodiment, the computer circuitry is further configured to transmit a D2D cluster coordinator assignment acceptance to a first UE in the D2D cluster that sends the D2D cluster coordinator self-assignment request and the power capacity level or the battery capacity level is above the threshold. In one embodiment, the computer circuitry is further configured to enable a hand over of a D2D UE in the D2D cluster to an other D2D cluster coordinator in an other D2D cluster. In another embodiment, the computer circuitry is further configured to receive a cluster association request at the eNB from an other UE to join the D2D cluster and communicating, to the D2D cluster coordinator UE, a cluster association approval for the other UE to associate with the D2D cluster coordinator UE to join the D2D cluster.

In one embodiment, the computer circuitry is further configured to receive, at the eNB, a cluster information message from the D2D cluster coordinator UE, wherein the cluster information message includes: a D2D bandwidth request for D2D communication by UEs in the D2D cluster; an interference report, regarding interference between the UEs in the D2D cluster or interference between UEs in adjacent D2D clusters; a transmit power control message; a request to move a D2D communication frequency to a different frequency band; a request to add an other UE to the D2D cluster; and/or a request to remove at least one UE from the D2D cluster. In another embodiment, the computer circuitry is further configured to use the interference report, by the eNB, to determine when to combine or split D2D clusters.

FIG. 13 illustrates a method for forming a D2D communication cluster. The method can comprise searching, by a user equipment (UE), for a D2D discovery beacon communicated from a D2D cluster coordinator, as in block 1310. The method can further comprise transmitting a D2D cluster coordinator self-assignment request from the UE to an eNB when the D2D discovery beacon is not received for a selected period of time, as in block 1320. The method can also comprise receiving a D2D cluster coordinator self-assignment request approval from the eNB to configure the UE as a D2D cluster coordinator, as in block 1330. The method may further comprise forming a D2D cluster by the D2D cluster coordinator to enable D2D communication between UEs in the D2D cluster, as in block 1340.

In one embodiment, the method further comprises transmitting a D2D discovery beacon to the UEs located within a coverage area of the D2D cluster and receiving a join request from at least one of the UEs to join the D2D cluster. In another embodiment, the method further comprises communicating a join request approval from the D2D cluster coordinator to the at least one UE. In another embodiment, the method further comprises communicating to the eNB the join request of the at least one UE from the D2D cluster coordinator and receiving a join request approval from the eNB at the D2D cluster coordinator for the at least one UE to join the D2D cluster. In another embodiment, the method further comprises receiving a D2D bandwidth allocation request from at least one UE in the D2D cluster, scheduling bandwidth for the at least one UE, and transmitting a D2D bandwidth allocation message to the at least one UE within the D2D cluster to enable the at least one UE to determine when bandwidth is allocated for the at least one UE to communicate with another UE in the D2D cluster.

FIG. 14 provides an example illustration of the wireless device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, or other type of wireless device. The wireless device can include one or more antennas configured to communicate with a node or transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), a remote radio unit (RRU), a central processing module (CPM), or other type of wireless wide area network (WWAN) access point. The wireless device can be configured to communicate using at least one wireless communication standard including 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and Wi-Fi. The wireless device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The wireless device can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.

FIG. 14 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the wireless device. The display screen can be a liquid crystal display (LCD) screen, or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or another type of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. A non-volatile memory port can also be used to provide data input/output options to a user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. A keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

Various techniques, or certain aspects or portions thereof, can take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device can include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements can be a RAM, EPROM, flash drive, optical drive, magnetic hard drive, or other medium for storing electronic data. The base station and mobile station can also include a transceiver module, a counter module, a processing module, and/or a clock module or timer module. One or more programs that can implement or utilize the various techniques described herein can use an application programming interface (API), reusable controls, and the like. Such programs can be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) can be implemented in assembly or machine language, if desired. In any case, the language can be a compiled or interpreted language, and combined with hardware implementations.

It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module can be implemented as a hardware circuit comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

Modules can also be implemented in software for execution by various types of processors. An identified module of executable code can, for instance, comprise one or more physical or logical blocks of computer instructions, which can, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but can comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

Indeed, a module of executable code can be a single instruction, or many instructions, and can even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network. The modules can be passive or active, including agents operable to perform desired functions.

Reference throughout this specification to “an example” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in an example” in various places throughout this specification are not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositional elements, and/or materials can be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention can be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below. 

What is claimed is:
 1. A user equipment (UE) operable to communicate in a device to device (D2D) network, having computer circuitry configured to: listen for a D2D discovery beacon at the UE for a predetermined period of time; self-assign the UE as a D2D cluster coordinator when the D2D discovery beacon has not been received by the UE for the predetermined period of time; form a D2D cluster to enable D2D communication between D2D UEs in the D2D cluster; and transmit a D2D discovery beacon from the D2D cluster coordinator to the D2D UEs within the D2D cluster.
 2. The computer circuitry of claim 1, wherein the computer circuitry is further configured to: receive a join request at the D2D cluster coordinator from a D2D UE in the D2D cluster to join the D2D cluster; and communicate a join request approval to the D2D UE.
 3. The computer circuitry of claim 1, wherein the computer circuitry is further configured to: receive a D2D bandwidth allocation request for bandwidth from at least one D2D UE in the D2D cluster; schedule a communication period for the at least one D2D UE in the D2D cluster; and transmit scheduling information for the communication period to the at least one D2D UE in the D2D cluster to enable the at least one D2D UE to determine when the bandwidth is allocated for the at least one D2D UE to communicate with another D2D UE in the D2D cluster.
 4. The computer circuitry of claim 1, wherein the computer circuitry is further configured to coordinate scheduling information of each of the D2D UEs in the D2D cluster to reduce interference between the D2D UEs.
 5. A user equipment (UE) operable to communicate in a device to device (D2D) network, having computer circuitry configured to: receive, at the UE, a D2D discovery beacon from a D2D UE coordinator in a D2D communication cluster; transmit a join request to the D2D UE coordinator, to join the D2D communication cluster; and receive a join request approval message to join the D2D communication cluster.
 6. The computer circuitry of claim 5, wherein the computer circuitry is further configured to: transmit a D2D bandwidth allocation request to the D2D UE coordinator in the D2D communication cluster; receive a scheduling information from the D2D UE coordinator for communicating with a D2D UE in the D2D communication cluster; and transmit data from the UE to the D2D UE in the D2D communication cluster at a selected time based on the received scheduling information.
 7. The computer circuitry of claim 5, wherein the computer circuitry is further configured to transmit a join request to an adjacent D2D UE coordinator that is located in an adjacent D2D communication cluster to the D2D communication cluster.
 8. The computer circuitry of claim 5, wherein the computer circuitry is further configured to send a multicast transmission request to the D2D UE coordinator to schedule a multicast by the UE to other UEs in the D2D communication cluster.
 9. The computer circuitry of claim 5, wherein the computer circuitry is further configured to request to associate or request to dissociate with the D2D UE coordinator based on a receiving power of the D2D discovery beacon at the UE.
 10. The computer circuitry of claim 5, wherein the computer circuitry is further configured to request a handover from the D2D UE coordinator to an other D2D UE coordinator based on a receiving power of the D2D discovery beacon at the UE.
 11. The computer circuitry of claim 5, wherein the computer circuitry is further configured to receive D2D discovery beacons at the UE from a plurality of D2D UE coordinators, wherein each D2D UE coordinator is located in a separate D2D communication cluster.
 12. An enhanced node B (eNB) operable to form a device to device (D2D) communication cluster, having computer circuitry configured to: receive a D2D cluster coordinator self-assignment request from a user equipment (UE) at an enhanced node B (eNB); transmit a D2D cluster coordinator assignment acceptance from the eNB to the UE to form a D2D cluster coordinator UE; and form a D2D cluster by the eNB to enable D2D communication between D2D UEs, wherein the D2D cluster coordinator UE coordinates the D2D communication between the D2D UEs in the D2D cluster.
 13. The computer circuitry of claim 12, wherein the computer circuitry is further configured to: receive a D2D radio bearer setup request from an other UE in the D2D cluster at the eNB; and establish a D2D radio bearer for a D2D pair that includes the other UE.
 14. The computer circuitry of claim 13, wherein the computer circuitry is further configured to establish the D2D radio bearer to provide a desired quality of service (QoS).
 15. The computer circuitry of claim 12, wherein the computer circuitry is further configured to determine a D2D cluster coordinator UE in the D2D cluster to receive the D2D cluster coordinator assignment based on a power capacity level or a battery capacity level threshold of the UE in the D2D cluster.
 16. The computer circuitry of claim 15, wherein the computer circuitry is further configured to transmit a D2D cluster coordinator assignment acceptance to a first UE in the D2D cluster that sends the D2D cluster coordinator self-assignment request and the power capacity level or the battery capacity level is above the threshold.
 17. The computer circuitry of claim 12, wherein the computer circuitry is further configured to enable a hand over of a D2D UE in the D2D cluster to an other D2D cluster coordinator in an other D2D cluster.
 18. The computer circuitry of claim 12, wherein the computer circuitry is further configured: receive a cluster association request at the eNB from an other UE to join the D2D cluster; and communicate, to the D2D cluster coordinator UE, a cluster association approval for the other UE to associate with the D2D cluster coordinator UE to join the D2D cluster.
 19. The computer circuitry of claim 12, wherein the computer circuitry is further configured to receive, at the eNB, a cluster information message from the D2D cluster coordinator UE, wherein the cluster information message includes: a D2D bandwidth request for D2D communication by UEs in the D2D cluster; an interference report, regarding interference between the UEs in the D2D cluster or interference between UEs in adjacent D2D clusters; a transmit power control message; a request to move a D2D communication frequency to a different frequency band; a request to add an other UE to the D2D cluster; or a request to remove at least one UE from the D2D cluster.
 20. The computer circuitry of claim 12, wherein the computer circuitry is further configured to use the interference report, by the eNB, to determine when to combine or split D2D clusters.
 21. A method for forming a device to device (D2D) communication cluster, comprising: searching, by a user equipment (UE), for a D2D discovery beacon communicated from a D2D cluster coordinator; transmitting a D2D cluster coordinator self-assignment request from the UE to an enhanced node B (eNB) when the D2D discovery beacon is not received for a selected period of time; receiving a D2D cluster coordinator self-assignment request approval from the eNB to configure the UE as a D2D cluster coordinator; and forming a D2D cluster by the D2D cluster coordinator to enable D2D communication between UEs in the D2D cluster.
 22. The method of claim 21, further comprising: transmitting a D2D discovery beacon to the UEs located within a coverage area of the D2D cluster; and receiving a join request from at least one of the UEs to join the D2D cluster.
 23. The method of claim 22, further comprising communicating a join request approval from the D2D cluster coordinator to the at least one UE.
 24. The method of claim 21, further comprising: communicating to the eNB the join request of the at least one UE from the D2D cluster coordinator; and receiving a join request approval from the eNB at the D2D cluster coordinator for the at least one UE to join the D2D cluster.
 25. The method of claim 21, further comprising: receiving a D2D bandwidth allocation request from at least one UE in the D2D cluster; scheduling bandwidth for the at least one UE; and transmitting a D2D bandwidth allocation message to the at least one UE within the D2D cluster to enable the at least one UE to determine when bandwidth is allocated for the at least one UE to communicate with another UE in the D2D cluster.
 26. The method of claim 21, further comprising the cluster coordinator serving as a mobile Pico node.
 27. The method of claim 26, further comprising dynamically optimizing the location and coverage of the mobile Pico node based on D2D traffic. 